Silencer



April 29, 1930. MAXlM ET AL 1,756,29;

SILENCER Filed June 27, 1927' INV ENTO 3y g id/ im A TTORNEYS.

Patented Apr. 29', 1930 UNITED STATES PATENT OFFICE HIRAM PERCY MAXIM AND ROLAND IB. BOURNE, OF HARTFORD, CONNECTICUT, AS-

SIGNORS. BY MESNE ASSIGNMENTS, TO THE MAXIM SILENCER I COMPANY, OF HARTFORD, CONNECTICUT, A CORPORATION OF CONNECTICUT SILENCEB Application I filed June 27,

This invention appertains to a wave damping device for the silencing of noise, or for the attenuating, attriting, and impeding of certain waves or pulsations in a gaseous medium which may not be ordinarily classified as sound but which partake of the same nature thereof.

This invention aims at the accomplishment of its purpose by assembling a plurality of identical spirally wound sheets in superposed interwound relation between two separate header portions, said sheets forming a grouping outwardly confined by a substantlally cylindrical form and inwardly surround ng a substantially cylindrical central space or chamber so that the gases may pass through an opening in one of the headers into the central chamber and from there through the various narrow passages formed between adjacent spirally wound sheets to the exterior. In some cases, one or more additional groupings of similarly shaped and interwound sheets is arranged between headers common to all groupings, consecutive groupings concentrically enclosing the next inner grouping with an annular chamber between. Further combinations of several such concentric groupings within a common shell are possible.

The object of the invention is to improve and simplify the construction of such silencers, whereby the cost of manufacture may be lessened and the assembly of parts greatly facilitated. In this connection, a feature of importance resides in the means for spacing the spirally wound sheets one from the other and for spacing concentrically disposed groupings one from the other, as will hereinafter appear. I r

Referring to the drawings which show a preferred embodiment of the invention :--v

Fig. 1 is a side elevation of a sheet group ing apart from the headers; p

Fig. 2 is an end View of the same showing a second and smaller grouping in'nested re= lation therewith; and

'Fig. 3 is a longitudinal section taken I through line 33 of Fig. 2 of the two concentric sheet groupings mounted between headers to form a complete silencing apparatus.

' Referring more particularly to the draw-.

1927. Serial N0. 201,951.

ings, the sheet groupings (separately shown in Figs. 1 and 2) are made up of a plurality of superposed spirally wound sheets 1 which are spaced apart as shown to provide a plurality of passages 2 arranged in parallel and leading from the interior chamber to the exterior. The several sheets 1 are preferably arranged with the ends in overlapping relation, the inner straight edges 4 of said sheets being preferably spaced apart at equal distances and the outer edges 5 of said sheets likewise being spaced apart at equal distances. In this way, equi-spaced inlets for the several passages 2 are provided at the interior of said chamber and equi-spaced outlets for said passagps are provided exteriorly.

he sheetsl are preferably spaced apart a very small distanceapproximately onefiftieth of an inch'so as to provide a passage 2 of an extremely narrow or small depth relative to the length of said passage. In our preferred form of silencing unit, the relation between the depth of each passage to its length is approximately in the proportion of one to two hundred. These passages are much narrower in depth than passages heretofore employed in silencer construction and we have found that the dissipation of wave energy is greatly increased in such small passages, probably due to the far greater scrubbing action and attrition to which said waves are subjected than in larger passages. Such narraW passages are particularly effective in the suppression of waves of high frequency. These passages 2 may be as small as is practical to make and space them and yet provide a free flow of gas therethrough. In order to take care of any desired volume of gas with such a silencing unit, thenarrowpassages described may be multiplied in number to any reasonable extent. The number of passages possible in such an arrangement as shown will obviously bea function ofthe inner circle on number of such sheets in the manner described offers considerable difliculty unless suitable spacing means are provided for separating the sheets.

The means for spacing apart the sheets forv each silencing unit preferably consist of an integral offset projection or bead which may be rolled into the sheet lengthwise thereof for preferably displaced in staggered relation with the beads-of the next adjacent sheet, as clearly appears in Fig. 3. The beads being distributed over the entire surface of the sheets will also serve to subdivide the spirally wound passages intoa number of channels of smaller width whereby the scrubbing action is further augmented due to an increased friction surface for the gases passing on both sides of a bead.

' When it is desirable to combine two or more sheet groupings, they may be made of differentdiameters and arranged in nested reuted through the various inlets of said insidefurther groupings as are employed and it is lation one within the other, as shown in Fig. 2.. In this way concentric double, treble or multiple'groupings can be formed. Means should be provided for spacing said concentric groupings and in our preferred embodiment this consists of turning up integral corner portions 7 at the outer ends 5 of the sheets making up the inside grouping, which turned upportionswillcontactwiththeinnerportions of the sheets 1 in the outside grouping. In forming a complete silencing apparatus, two such concentric groupings may be mounted between a header member 8 having an inlet 9 and a header member 10 the entire assembly being held together by suitable tie bolts 11, as shown in Fig. 3. It will be observed by this construction that an interior chamber 12 within the inside groupings is provided and likewise an annular space or secondary chamber 13 is provided between the two groupings, as shown.

,In operation, it will be understood that gases-and sound waves entering the interior chamber of a sheet-grouping will be distribchamber and flow through the spiral passages to the exterior, the sound waves bein'g subdi-J vlded, scrubbed and attenuated during the' process so as to emerge with very little energy. This process is repeated through such v to be understood that various combinations and arrangements, other than as shown, of such grouplngs 1n cascade may be employed to meet the exigencies of each situation in connection with the handling of sound silencing problems.

' What we claim is:

1. A silencer comprising two headers one of them with an opening therethrough, a grouping of substantially identical, spirally wound sheets, whose spirally wound edges abut said two headers, said sheets arranged in superposed interwound relation so that in a cross-section parallel to the headers the inner and the outer ends of the wound edges are substantially symmetrically spaced on an inner and an outer concentric circle respectively, the inner straight edges of the sheets togetherwith the header walls defining an inner centrally extending chamber communicating with the exterior through said open- 7 ing, and a plurality of integrally formed projections on said spirally wound sheets, said projections being parallel to the header engaging edges of the sheets and being axially displaced with respect to each other on two adjacent sheets, thus defining the depth and abut said two hegders, said sheets arranged in superposed intyrwound relation so that in a cross-section pa allel to the headers the inner and the outer ends of the wound edges are substantially symmetrically spaced on an inner. and an outer concentric circle respectively, the inner straight edges of the sheets together with the header walls defining an. in-

ner centrally extending chamber communicatingwlth the exterior through said opening, and'a plurality of integrally formed pro ections on said spirally wound sheets, said projections being about equidistantly distributed over the whole surface of the sheets parallel to the header engaging edges of the sheets and axially displaced with respect to each other on two adjacent sheets, thus definng the depth and width of the spirally'windmg passages formed between two adjacent sheets.

3. A silencer comprising of them with an opening therethrough, a grouping of substantially identical, spirally edges are substantially symmetrically spaced on an innerand anouter concentric circle respectively, the inner straight edges of the sheets together with the header walls defin ing an inner centrally-extending chamber communicatin I with the exterior through I said opening, a plurality of integrally formed two headers one wound sheets, whose spirally wound edges projections on said spirally wound sheets,

said projections being parallel to the header engaging edges of the sheets and being axially displaced with respect to each other on two adjacent sheets, thus defining the depth and width ofthe spirally winding passages formed between two adjacent'sheets in the grouping, one or more additional groupings of similarly formed spirally wound sheets arranged between said same headers concentrically about the first grouping on circles of large enough diameter to leave annularchambers bet-ween two successive groupings, the uniform width of these annular chambers being secured by bent corner portions of adjacent spiral sheets.

Intestimony whereof we have affixed our signatures. v

HIRAM PERCY MAXIM. ROLAND B. BOURNE. 

